This invention relates generally to furnaces and, more particularly, to an air baffle diverter vane for diverting air over a particular portion of a furnace heat exchanger for preventing hot spots.
Residential furnaces typically include a plurality of heat exchanger panels or cells arranged in parallel relationship, with the air to be heated being circulated by a blower so as to pass between the panels and over the surfaces of the panels, to be heated. The panels have associated burners for heating the air within the panels, and an inducer may be employed to draw the heated air through the panels and discharge them to a flu.
One form of heat exchanger that is commonly used in such furnaces is a so-called clamshell heat exchanger, wherein two stamped metal shells are fastened together to form a single panel having a plurality of serpentine passages, or passes, through which the hot gases can be caused to flow. Thus, a burner heats the air at an inlet end thereof, and the hot gases pass through successive passes and finally come out of the exit end of the panel to eventually be discharged to the flu. As the gases pass from the inlet to the exit end of the panel, they are cooled by the air being circulated over the surface of the panel. Thus, the gases in the first pass are at substantially higher temperatures than those downstream thereof, and care must be taken to prevent the occurrence of excessive temperatures. In particular, hot spots are most likely to occur in the vicinity of the first return bend between the first and second passes. These hot spots cause exposure to high temperatures that can cause excessive strain levels in the material of the heat exchanger structure and may eventually lead to failure.
Typically, the peak temperatures on the outside of the outboard heat exchanger panels are higher than the temperature on the inboard heat exchanger panels. In an effort to obtain greater circulation airflow over the outer sides of these outboard heat exchanger panels, so-called sidewall baffles have been applied to better channel the circulation airflow along the outer surfaces of the outdoor panels. Such sidewall baffles are generally fastened to the furnace casing or to the blower shelf and extend substantially vertically upwardly in parallel relationship with its associated outboard heat exchanger panel. While these sidewall baffles are useful in improving the air circulation over the outboard panels and thereby preventing excessive temperatures in this area, they may not be sufficient to prevent hot spots, especially in the sensitive area of the first return bend.
It is therefore an object of the present invention to provide an improved furnace heat exchanger apparatus.
Another object of the present invention is to provide a heat exchanger apparatus with reduced thermal stress.
Yet another object of the present invention is the provision for maintaining the temperatures on the surface of an outboard heat exchanger panel within acceptable limits.
Still another object of the present invention is the provision in heat exchanger apparatus for lowering both the peak temperatures on the surface of an outboard heat exchanger.
Another object of the present invention is the provision in a heat exchanger apparatus for reducing the occurrence of hot spots in the first return bend of an outboard heat exchanger panel.
These objects and other features and advantages become more readily apparent on reference to the following descriptions when taken in conjunction with the appended drawings.
Briefly, in accordance with one aspect of the invention, a diverter vane is added to the inboard side of a sidewall baffle and extends inwardly toward an outboard heat exchanger panel so as to divert a portion of the circulation airflow to particular areas on the heat exchanger panel surface which might otherwise experience hot spots.
In accordance with another aspect of the invention, the diverter vane is permanently affixed to and extends substantially normally from said sidewall baffle.
In accordance with yet another aspect of the invention, the diverter vane is disposed at an oblique angle with respect to the heat exchanger passes, with its lower end being located near a central point of said first pass and its upper end being located near the end of said first return bend.